Systemic lupus erythematosus (SLE) is an autoreactive T cell mediated autoimmune disease. Immunization with inactivated autoreactive T cells may induce idiotype anti-idiotypic reaction to deplete specific subsets of autoreactive T cells involved in SLE. Six SLE patients unsuitable or refused to use immunosuppressants were treated with T cell vaccination. Their clinical manifestations and laboratory parameters including mixed lymphocyte reactions were evaluated. Autoreactive T cell clones were derived from peripheral blood mononuclear cells of the patients and 1 X 10(7) irradiated T cells were inoculated subcutaneously at 0, two, six and eight weeks, respectively. The enrolled patients were followed up for 32-40 months at an interval of three to six months. The clinical characteristics and laboratory abnormalities improved after inoculation without increasing the dose of corticosteroids and immunosuppressants in most patients. SLE disease activity index (SLEDAI) scores decreased. Proliferative responses against the T cell vaccine were observed in four of six patients. At the time of this report, the six patients remain in clinical remission. No significant side effect from the vaccination was noticed during the follow-up period. The results of this pilot study indicate that T cell vaccination is a safe and effective treatment in SLE.